Free Swinging Piston Heat Machine

ABSTRACT

The invention relates to positive-displacement free-piston heat machines with variable working chambers, which could be applied as an internal or external combustion engine, compressor, pump. The machine comprises two analogous assemblies of pistons, each consisting of two or more vanes having form of symmetrical star and attached to the hub. The assemblies of pistons are placed in the cylindrical cavity that is limited by two concentric cylindrical surfaces and two planes at the ends. The vanes the different assemblies are alternately displaced in the cavity. When the assemblies of pistons swing in opposite directions, variable working chambers are got between the adjacent vanes. The external loading or driving devices are connected directly to the assemblies of pistons either by coaxial shafts, radial junctions, planar or cylindrical rings. The machine with two bodies swinging in opposite direction presents well-balanced mechanical system, and vibration of the frame is avoided.

Free swinging piston heat machine belongs to the positive displacementheat machines, whose operation is grounded by variables working volumes,and which are applied as internal combustion engines (spark ignition,diesel), external combustion engines (steam engines, Stirling engines),and as compressors, pumps, expanders.

There are known the free reciprocating piston internal combustionengines, whose stroke of piston (or pistons) is not limited bymechanical means and which could vary. These engines are destined fordirect drive (without of movement transformer) of oscillating electricalgenerators or other devices with periodical movement (compressors,piledrivers). The free-piston heat machines have some advantages incomparison to the machines with fixed piston stroke, because variationof the piston stroke enables additionally to control duty of themachine. In the free-piston internal combustion engines it is possibleto optimise process of combustion from the viewpoint of efficiency andminimised pollution. Absence of the motion transformers, that is,realisation of the direct drive principle, not only simplifies structureof the device, but also enables to decrease energy losses that areinevitable in any transformer of motion.

There is known the single-sided free-piston internal combustion enginehaving one cylinder “Free-piston engine and method for the conversion ofenergy stored in fuel into electrical energy in a free-piston engine”(patent DE 04315046 A1, 10 Nov. 1994). A motion transformer is not usedin this device, but the spring for reverse of the piston is used. Thespring complicates structure of the device and decreases itsreliability. In addition, the mechanical system of the engine with onecylinder is unbalanced, which provokes large vibrations of the frame.Similar device of the free-piston engine driving an oscillatingelectrical generator is also presented as one variant in the patent ofFrench Republic N. 1309350, 8 Oct. 1962 “Dispositif électromagnétique detransrofmation d'énergie”.

There are known doubled free-piston internal combustion engine, thepistons in which move in opposite directions enabling to avoid vibrationof the frame—patent U.S. Pat. No. 4,154,200 A, 15 May 1979“Non-polluting heat machine with internal combustion”. The motiontransformer is absent in this engine, but other imperfection remains,that is the necessity of the springs for reverse of the pistons of thesingle-sided engine.

There are known the free-piston internal combustion engine having twodouble-sided cylinders operating in opposite sense, and driving anoscillating electrical generator. Such engines can be springless—seecorresponding variants of the patent of French Republic N. 1309350, 08Oct. 1962 “Dispositif électromagnétique de transrofmation d'énergie”. Inaddition, the doubled variant of such double-sided engines is providedtoo, in which vibration of the frame is eliminate. Consequently, suchfree-piston heat machine has most advantages.

However, in all free-piston engines with linear motion of pistons largefriction losses between the piston (or piston rings) and cylinder wall,or in other linear guides are inevitable. Moreover, the four-strokeoperation of such engines is well nigh impossible, while the two-strokeoperation is imperfect from the viewpoint of utilisation of the fuel andquality of the combustion process.

The friction of the pistons or their guides can be radically decreasedin the swinging (rotating) pistons heat machines.

There is known the swinging pistons internal combustion engine (patentDE 03303509 A1, 09 Aug. 1984 “Machines with double-acting pistons”), inwhich the pistons by two vanes of rectangular cross-section, which aresymmetrically attached to the cylindrical hub, pivot around the axis ofthe cylindrical form cavity. Four working chambers of the machines areformed between the two fixed vanes and two swinging vanes. Thefour-stroke and two-stroke operations of the engine are provided. In thelater case, a usage of the inlet and exhaust ports in the housing, whichare opened by the piston itself, is provided (instead of the valves).There is also known other four-stroke internal combustion engine ofanalogous structure (patent U.S. Pat. No. 5,086,732 A, 11 Feb. 1992“Four stroke concentric oscillating rotary vane internal combustionengine”). Both these engines have an advantage to compare with theengines of linear pistons that the rotating bearings are used as guidesof the swinging pistons without a friction of the pistons to the enginecylinder. The friction losses of the rotating bearings are markedlydecreased due to the lesser mutual speed of the sliding surfaces. Theseengines have compact and workable structure, because the housing cavityand swinging pistons are formed by planar and cylindrical surfaces.However, these engines have essential imperfections: the movementtransformer is applied, which transforms the oscillation of the pistonsinto continuous rotation, and which ipso facto are mechanically fixingthe pistons stroke; the mechanical system are unbalanced, and provokesvibration of the frame; the concrete strokes of the four-strokeoperation of the engine occur in the asymmetrically displaced workingchambers, which causes addition loads of the bearings and additionalvibration of the device.

There are known engines with two analogous coaxial assemblies ofpistons, in which the assemblies of pistons are formed by two wanes ofrectangular cross-section, which are symmetrically attached to thecylindrical hubs, and the piston's vanes move in the ring shaped cavityof rectangular cross-section forming four working chambers of variablevolume (see patents: U.S. Pat. No. 385,856 A, 7 Jan. 1975,“Reciprocating rotary engine”; DE 04014279 A1, 23 Jan. 1992,“Four-stroke, rotary vane IC engine—has vane rotating in one directiononly in circular, radial working chamber”; GB 02262569 A, 23 Jun. 1993,“Oscillatory rotating engine”; U.S. Pat. No. 5,537,973 A, 23 Jul. 1996,“Rotary engine with glow ignition system”). In all these devices thementioned above advantages of the rotary (or swinging) pistons enginesare realised, that is, the small friction in the rotary guides,compactness of the working chambers, and workable structure.Consequently, from this standpoint, the mentioned analogues are the mostallied to the invention. However, these analogues have essentialimperfections: in all cases, the transformers of movement are used thatrealise the unidirectional rotation of the assemblies of pistons withperiodically variable velocities, in this way achieving periodicalvariation of the working chambers; any external devices (engine's load)are also connected through the movement transformer, that is, usingunidirectional rotation of the shaft; the variable velocities of theassemblies of pistons provoke vibrations of the frame; the four-strokeengine operation is realised in four working chambers, but in anyinstance the combustion occurs only in one working chamber, thereforethe high-pressure zone is asymmetrical to the axis, which causesadditional vibration and load of bearings.

Essence of the invention. The free swinging piston heat machine has twoanalogous assemblies of pivoting pistons, each of which are formed bytwo or more vanes having a form of the symmetrical star, and attached tothe hub of assembly. The vanes of both pistons' assemblies are placed inthe cross-section ring shaped closed cavity limited by two concentriccylindrical surfaces and two plates at the ends. The machine's housingand corresponding surfaces of the assemblies of pistons (e.g. theexternal surfaces of the hubs) form the cavity. The cross-section ofvanes corresponds to the cross-section of the cavity, and vanes of thedifferent assemblies are alternately displaced in the cavity.

The assemblies of pistons could independently pivot around the axis ofhousing. The rotary guides (bearings) are arranged in the hubs. In thisway a friction between the vanes and housing is avoided, and totalfriction losses are markedly reduced, because only the losses in therotary bearings remain. Moreover, minimal clearance between the movablesurfaces could be realised, which could accomplish permissible leakagewithout additional elements of sealing and lubrication.

When the assemblies of pistons swing in opposite direction, the variableworking chambers between the adjacent vanes are formed. The number ofworking chambers is equal to total number of vanes of both assemblies ofpistons (that is, 4 or major even number of working chambers). If thisnumber is multiple to 4, the four-stroke operation of the internalcombustion engine can be realised. If it is multiple to 8, thesymmetrical four-stroke internal combustion engine must be realised(without additional vibration and load of the bearings).

The external loading or driving devices are connected directly (withouttransformer of movement) to the assemblies of pistons by coaxial shaftsor junctions arranged at the vane ends.

The centres of mass of the assemblies of pistons together with theconnected external moving bodies must be in the axis of rotation. Inthis way, the balanced mechanical system of tree bodies is got, whichdoes not provokes vibration of the frame, when the assemblies of pistonsswing synchronically in opposite directions.

FIG. 1 shows the free swinging pistons heat machine with two vanes inassemblies of pistons, and when the all working chambers have equalvolume.

FIG. 2 shows the same machine as in FIG. 1, only the two workingchambers are decreased, and others are increased.

FIG. 3 presents the assemblies of pistons with tree vanes.

FIG. 4 presents the heat machine, when the assemblies of pistons havefour vanes.

In FIG. 5 the assemblies of pistons with two vanes and with the coaxialshafts for connection external devices are shown.

In FIG. 6 the machine with enlarged ends of vanes having a radialjunctions to connect external devices is depicted.

FIG. 7 presents the assembly of pistons with two vanes having a planarring arranged at the ends of vanes for connection of external devices.

In FIG. 8 cross-section of the machine with the assemblies of pistons ofFIG. 7 is shown.

In FIG. 9 the separate assemblies of pistons having cylindrical ringsarranged at the vanes ends for connection of external devices.

In FIG. 10 the aggregate of two concentric heat machines is shown.

FIG. 11 shows the heat machine with a concentric oscillating rotatingelectrical machine.

The free swinging piston heat machine consists of housing containing acylindrical cavity. This cavity could be formed by separate parts of thehousing, for examples, as it is shown in FIG. 1: the cylindrical ringand two planar covers form the cavity (the cover 3 is shown uplifted).

There are two analogous assemblies of pistons 4 and 5 in the cavity ofhousing. The assembly of pistons consists of cylindrical hub 6. Two ormore vanes of rectangular cross-section are attached to the hub (seeFIGS. 1, 3, 4). The vanes are arranged in form of the symmetrical star.The assemblies of pistons are placed in the cylindrical cavity and canpivot around its axis using bearings arranged in the hubs.

The assemblies of pistons can have coaxial shafts 8, 9 to connectexternal devices (see FIG. 5).

The assemblies of pistons can have radial junctions 10 arranged in theenlarged ends of vanes to connect external devices (see FIG. 6). Thesejunctions move in the holes 11 of housing, the holes being closed by theenlarged ends of vanes.

The planar rings 12, 14 could be arranged at the ends of vanes toconnect external devices (see FIGS. 7, 8). These rings can move in thegaps between the cylindrical part of housing and the covers. The planarrings have the holes 13 for junctions 15 of the separate housing parts.The sealing rings 16 could be arranged between the planar rings and theparts of housing.

The cylindrical rings 17, 18 could be arranged at the ends of vanes toconnect external devices (see FIG. 9). The height of these rings isapproximately equal to half height of the cylindrical cavity. In thiscase the working cavity is formed by surfaces of the covers 2, 3, hubs6, and cylindrical rings 17,18.

If the planar or cylindrical rings of junction are used (see FIGS. 7, 8,9), a few free swinging pistons heat machines could be arrangedconcentrically. In this case, the vanes of second heat machine 19, 20are attached to the junction rings. Such set of two concentric heatmachines is shown in FIG. 10.

Operation of the free swinging piston heat machine occurs when theassemblies of pistons swing (oscillate) in opposite directions. In thisway variable working volumes are formed between the adjacent vanes ofthe different assemblies of pistons (see FIGS. 1, 2).

If the heat machine is used as a compressor or pump, the suction andpressure valves are arranged in the machine's housing, which connect Anoscillating electrical motor can direct drive such compressor of pump.The rotors of motor are connected with the assemblies of pistons throughthe corresponding junctions of external devices (see FIG. 11). In thiscase, the oscillating electrical motor can control the amplitude,frequency, spectrum, and centre of oscillation of the assemblies ofpistons.

If the heat machine is used as an internal or external combustionengine, and expander, the controlled valves (e.g. driven by anelectrical drive of impulse movement) are arranged in the machine'shousing, which connect the working volumes with the systems of inlet andexhaust. The injectors could also be arranged in the housing. The heatengine can direct drive an oscillating electrical generator with tworotors 22 and 23 connected by corresponding junctions, while the statorof the electrical generator could be undivided (see FIG. 11). Theelectrical machine of the aggregate can be used for engine starting aswell as to control the oscillation amplitude of pistons (that is, thecompression ratio), spectrum and centre of oscillation.

Commonly, the conditional pressure developing by an electrical machineis less than pressure of a heat machine. Therefore it is expedient toarrange the electrical machine outside of the heat machine, as it isshown in FIG. 11. In this way, the compact structure of the aggregatecan be realised with optimal utilisation of components of the directmechanical transmission.

Both the two-stroke operation and four-stroke operation of internalcombustion engine can be realised in the free swinging piston heatmachine, because in any case there are no less than 4 variable workingchambers. It is expedient to use heat machine with 8 working chambers(see FIG. 4) for four-stroke operation of the internal combustionengine. In this instance the four-stroke internal combustion enginebecomes well symmetrised without additional vibration and load of thebearings.

If the heat machine operate as two-stroke internal combustion engine,the inlet and exhaust ports can be arranged in the housing, and theseports can be opened and closed by the swinging pistons themselves.

When the concentric aggregate of several heat machines is used (FIG.10), different variants of such aggregate are possible. For example, onemachine can operate as an internal combustion engine, and can be used ascompressor (including a compressor of the scavenging of the internalcombustion engine). A doubled heat machine can also be used as two-stagecompressor.

Rotary bearings having small frictional losses are used as guides in thefree swinging pistons heat machine. The vanes and rings of junctions isnot guides, therefore they could operate without wear and frictionallosses. The precise rotary bearings enable to realise minimal clearancebetween the movable surfaces, and machine can operate without additionalelements of sealing and lubrication.

In all cases, the free swinging pistons heat machine operates as wellbalanced system of three bodies without vibration of the frame.

1. The free swinging pistons heat machine without movement transformer,having a housing with cylindrical cavity and two analogous assemblies ofpistons, which each consist of the hub and attached vanes and can pivotaround axis of the cylindrical cavity, ipso facto having a possibilityof the vanes to move in the cylindrical cavity, is characterized by anarrangement of two or move pistons' vanes in form of symmetrical star,the assemblies of pistons being non-connected mechanically, and whichswing in opposite directions, and in this way the variable workingvolumes are obtained, number of which is equal to the total number ofvanes of both assemblies of pistons.
 2. The free swinging pistons heatmachine of claim 1 wherein external devices (driving or loading) aredirectly connected to the assemblies of pistons swinging in oppositedirections.
 3. The free swinging pistons heat machine of claims 1, 2wherein the hubs of piston's assemblies have coaxial shafts to connectexternal devices.
 4. The free swinging pistons heat machine of claims 1,2 wherein the junctions to connect external devices are arranged at theends of vanes having possibility to move in holes of the housing.
 5. Thefree swinging pistons heat machine of claims 1, 2 wherein the planarrings to connect external devices are attached to the ends of vanes,which are inserted in gaps between parts of the housing.
 6. The freeswinging pistons heat machine of claims 1, 2 wherein the cylindricalrings to connect external devices are attached to the ends of vanes, andthese rings form external part of surface of the cylindrical cavity. 7.The free swinging pistons heat machine of claims 1, 2, 5, 6 wherein theanalogous vanes of other free swinging pistons heat machine areconnected to the junction rings, in this way forming an aggregate ofseveral concentrically arranged heat machines.
 8. The free swingingpistons heat machine of claims 1-7 wherein the valves for connection ofworking chambers with external systems of the gas are arranged in thehousing.
 9. The free swinging pistons heat machine of claims 1-7 whereinthe inlet and exhaust ports can be arranged in the housing, and theseports can be opened and closed by the pistons' vanes, when the machineoperates as an internal combustion engine.